information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

A red seaweed (Heterosiphonia plumosa)

Distribution data supplied by the Ocean Biogeographic Information System (OBIS). To interrogate UK data visit the NBN Atlas.



Heterosiphonia plumosa is a red to deep crimson seaweed which appears black when dried. This species has a flattened, fern-like appearance with a hairy thallus growing from a discoid holdfast. The fronds are flat or slightly cylindrical up to 20 cm in length and 0.5 cm in diameter at the base, tapering towards the apex. The primary branching from the main frond occurs in a single plane, and is alternately, yet irregularly spaced with up to 1 cm between each branch. Each branch is bare at the base, with the rest bearing an irregular and alternately arranged series of smaller secondary branches. The secondary branches are progressively shorter towards the apex, and each branch bears numerous pointed branchlets giving an overall tufted and feather-like appearance.

Recorded distribution in Britain and Ireland

Widely recorded throughout the coasts of Britain and Ireland, especially the south west but is rarely recorded on the north east Scottish coasts.

Global distribution



This species grows on rocks and as an epiphyte on seaweeds such as Laminaria in the lower littoral and sublittoral.

Depth range


Identifying features

  • Red to deep crimson in colour.
  • Hairy thallus up to 20 cm in length and 0.5 cm in diameter at the base.
  • The holdfast is discoid.
  • Alternate and irregular primary and secondary branching.
  • Additional branchlets give a feather-like appearance.

Additional information

Heterosiphonia plumosa is a perennial (life cycle >2 years) species, reproducing mainly during the summer and autumn. The cystocarps of Heterosiphonia plumosa are ovate and borne near the base of the branchlets, as are the tetrasporangia in asexual individuals, which are lanceolate and stalked (Dickinson, 1963). Both can be easily distinguished under a hand lens.

Heterosiphonia plumosa has several recorded variations, most notably Heterosiphonia plumosa f. palens which is typically slender and up to 7.5 cm in length. The fronds are smooth with evenly spaced branches and commonly occurs in deeper coastal waters (Dickinson, 1963).

Listed by

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Further information sources

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  1. Dickinson, C.I., 1963. British seaweeds. London & Frome: Butler & Tanner Ltd.

  2. Foster-Smith, J. (ed.), 2000. The marine fauna and flora of the Cullercoats District. Marine species records for the North East Coast of England. Sunderland: Penshaw Press, for the Dove Marine Laboratory, University of Newcastle upon Tyne.

  3. Gibson, R., Hextall, B. & Rogers, A., 2001. Photographic guide to the sea and seashore life of Britain and north-west Europe. Oxford: Oxford University Press.

  4. Hiscock, S., 1986b. A field key to the British Red Seaweeds. Taunton: Field Studies Council. [Occasional Publication No.13]

  5. Howson, C.M. & Picton, B.E., 1997. The species directory of the marine fauna and flora of the British Isles and surrounding seas. Belfast: Ulster Museum. [Ulster Museum publication, no. 276.]

  6. Laverack, M.S. & Blackler, D.M., 1974. Fauna & Flora of St. Andrews Bay. Scottish Academic Press (Edinburgh & London).

  7. Maggs, C.A. & Hommersand, M.H., 1993. Seaweeds of the British Isles: Volume 1 Rhodophycota Part 3A Ceramiales. London: Natural History Museum, Her Majesty's Stationary Office.

  8. MarLIN (Marine Life Information Network), 2005. SEArchable BEnthic Data (SEABED) Map [on-line]. Data Access Sub-programme, Marine Life Information Network for Britian and Ireland,

  9. National Biodiversity Network (NBN) Atlas website. Available from:  Accessed 01 April 2017

  10. Picton, B.E. & Costello, M.J., 1998. BioMar biotope viewer: a guide to marine habitats, fauna and flora of Britain and Ireland. [CD-ROM] Environmental Sciences Unit, Trinity College, Dublin.


This review can be cited as:

Rowley, S.J. 2008. Heterosiphonia plumosa A red seaweed. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 24-09-2018]. Available from:

Last Updated: 03/07/2008